Thanks to the always inquisitive PD of JRfm-The Peak/Vancouver Gord Eno, A&O recently was conveyed an excellent explanation from BBM on the technology of the PPM device:

"We now measure everything in ﬁfteen second segments. Yes, seconds. It takes keeping a listener ﬁfteen seconds for us to be in the game. If we win three out of the four ﬁfteen second segments we win that minute. If we get two out of four, the station that wins the ﬁrst ﬁfteen seconds wins the minute."

Now, add to that. You must also hold onto them for at least three 15 second periods inside every minute.

Technically, you need the last best "code" in the 15 seconds to be ascribed the first 15 seconds.

That last best code could come in the first second or the 15th second. If you're not familiar with code qualities and what this does to the assignment of the 15 seconds to the last best code, contact your BBM or ARB rep who can lessen your need for aspirin as you contemplate these technical realities.First, of course, if we donʼt keep them for the ﬁrst ﬁfteen seconds weʼre not even in the game.

Really, you only need to have the last best code in each 15 seconds, they don’t have to have stayed for the full 30.

But, it takes three 15 minute assignments of the last best code to outright “win” the full 60 seconds – and those three 15 second assignments don’t have to be consecutive, for example: first 15, station CAAA has last best code, Second 15, station CBBB has last best code, Third 15, station CAAA has last best code, and Fourth 15, station CAAA has last best code – minute goes to station CAAA.

Plus, we need them to stay for thirty seconds just to be in a tie. But it takes forty ﬁve seconds to win that minute. Then the battle begins all over again for the next minute.

Most minutes wins.

Eno joked with the BBM representative who offered the insights that the battleﬁeld has moved from quarter hours to quarter minutes.

The BBM rep's response was that things hadn’t really changed, and the focus as always should be on making better radio, because better radio gets better numbers.

Agreed, but knowing the mechanics of PPM helps us understand the ʻscienceʼ and how/when the radio consumerʼs impatience affects measurement.

Another revelation: the PPM code is not a constant stream.

Because the code likes to hide in the content the code stream is variable. When there is music, the code ﬂows along nicely. When there are gaps, such as spoken word, the code will embed itself behind any audio whatsoever, music, talk, random ambient noise will even encode.

Now, hereʼs the biggie. If there is four seconds of dead air there is no code.

The solution? Donʼt allow dead air.

Dead air (provided your dead air lasts for more than 15 seconds) means no code.

No code. No measurement. No measurement means weʼre kicked off the ﬁfteen second battleﬁeld and weʼre not even in the ﬁght.

To be totally factual, it only takes the last best code of the 15 second period.

It’s possible for there to be 4 different “last best codes” in each 15 seconds. Your code could come in as the ‘last best code’ on the 5th, 9th, 12th or even the 15th second with audio.